1. Field of the Invention
The present invention relates to a control apparatus for an electric oil pump that supplies oil to a drive system of a vehicle, for the generation of hydraulic pressure in a transmission of an idling stopped car, for the cooling of a running electric motor, or for an inverter of a hybrid car, or the like.
2. Description of Related Art
In this type of electric oil pump, when a temperature of oil (the oil temperature) is a very low temperature, viscosity significantly increases, the number of rotations of a pump driving electric motor is insufficient, and a preferable amount of the oil (the hydraulic pressure) cannot be discharged. To solve this problem, it has been considered for the oil temperature to operate the electric oil pump be set. However, there may be measurement errors due to fluctuations in characteristics of an oil temperature sensor, or the like. Therefore, even at an oil temperature at which the electric oil pump can actually be operated, the electric oil pump sometimes cannot be operated.
As a consequence, a temperature range in which the electric oil pump can be operated is narrowed, and control cannot be sufficiently exerted.
In technology disclosed in Japanese Laid-Open Patent Publication No. 2006-254616 as Patent Document 1, at the malfunction of the start of the electric oil pump, it is determined whether or not the electric oil pump is malfunctioning according to the outside air temperature in consideration of the influence of the oil viscosity, to prevent the occurrence of incorrect diagnosis.
However, also in Patent Document 1, it is not possible to expand the temperature range in which the electric oil pump can be operated. Moreover, the electric oil pump cannot be operated until the pump needs to be actually started. Therefore, at the malfunction of the start of the pump, the hydraulic pressure, flow rate or the like by the electric oil pump cannot be obtained, which has a large influence on a vehicle.